Breaking up with a long-term boyfriend can be one of the most difficult things you ever do. Even though you have decided it is the best decision to break up, you will have some emotional recovery to do afterwards. You probably still care deeply for this person, so it is important to try to minimize the amount of hurt that is inflicted on both of you throughout the process.
A good first step is to write down all of the reasons you have decided to break up with your boyfriend. Write for yourself. This is a way of clarifying your thoughts and motives for yourself. Decide what you want the result of the break up to be. Will it suit you best to maintain any kind of relationship with him? Will you be able to stay separated while maintaining contact? These are hard decisions that have different solutions for each personality type. Decide exactly what you want in advance and write it down so you can maintain your poise and resolve in the heat of the moment.
Make plans to meet him in a public place that still affords you some privacy such as a park or cafe. Never try to end a relationship of any significance on the phone, by text, email or any such impersonal method. It is unfair to both of you.
When you meet avoid skirting the issue--get to the point quickly. Express your desire to break it off firmly. Remain as calm as possible and don't raise your voice even if he does. You will probably have to answer some questions, but don't feel obligated to justify your decision extensively, long explanations can be painful for both of you and ultimately achieve nothing. Be respectful and avoid the trap of exchanging insults or accusations. Spiteful words will only make the experience more painful for both of you.
Whenever moments of weakness (which are more or less inevitable) come and you are tempted to call or see him, read back over what you wrote at the beginning of the process. Remind yourself why you decided to break up with your boyfriend in the first place. Remember that it is difficult to end any relationship that you have been in for a significant amount of time and that time and space are what will lessen the pain of a breakup.
Find a distraction that is not another love interest. Exercising and finding a new hobby are both healthy ways to recover your equilibrium. Immediately embarking upon a new romantic relationship is not. Rebounding can be harmful for your mental and emotional health. Find a way to be happy independently before allowing yourself to become involved in a new relationship.